a study of immunogenicity and seroconversion with sabin ipv schedules in china.

Conditions: Poliomyelitis

Summary: in april 2017, who recommended that a two-dose, inactivated poliovirus vaccine, ipv-only schedule at 4 months and 8 months of age can be used after polio eradication, with a schedule seroconversion target of at least 90%. however, there is no such data for china domestic sabin strain ipvs to support a 2-dose schedule among chinese infants. this research is to determine the seroconversion rates among two arms: group 1: two-dose schedule, infants will be received two doses of sabin ipv, the first dose at 4 month of age, and the second dose at 8-11 month of age. group 2: three-dose schedule, infants will be received three doses of sabin ipv at 2, 3 and 4 month of age respectively. this schedule is currently recommended by manufacture's package insert for routine use. the hypothesis is the seroconversion will be above 90% in both groups.

as a part of global polio eradication endgame immunization strategy, who requested all opv-using countries to introduce at least one dose of ipv into the routine immunization schedule. ideally ipv should be administered after 14 weeks of age, however an ipv-opv sequential schedule is acceptable if vapp is a concern. china stopped trivalent opv in routine immunization in may 2016, introduced one dose of ipv at 2 months followed by three doses of type i / iii bivalent opv (bopv) at 3 and 4 months and 4 years. a sabin strain ipv was licensed in january 2015, and a second sabin ipv was approved by china fda in september 2017. the production capacity will increase in the next few years and will meet the demands of an ipv-only schedule in china. other sabin ipvs are in clinical trial stages, which will lead to sufficient ipv production for china to export ipv. in april 2017, who/sage recommended that a two-dose, ipv-only schedule can be used after polio eradication, with a schedule seroconversion target of at least 90%. the recommendation was based in part on a study conducted in cuba using salk-ipv at 4 months and 8 months of age. considering that risk of polio virus transmission is decreasing over time, and that ipv - either domestic sabin-ipv or imported salk-ipv - is expensive (6 usd/dose) for a program serving a birth cohort of 18 million, an efficient two-dose, ipv-only schedule will be very competitive with a more traditional 4-dose ipv-only schedule. however, for domestic sabin ipvs, there are no such data to support a 2-dose schedule among chinese infants. the overall objective of this research is to determine the seroconversion rates of two reduced sabin ipv schedules in chinese children - a 2-dose schedule and a 3-dose schedule. group 1: two-dose schedule, infants will be received two doses of sabin ipv, the first dose at 4 month of age, and the second dose at 8-11 month of age. group 2: three-dose schedule, infants will be received three doses of sabin ipv at 2, 3 and 4 month of age respectively. this schedule is currently recommended by manufacture's package insert for routine use. the hypothesis is the seroconversion will be above 90% in both groups.

Eligibility criteria:
inclusion criteria: * parent or legal guardian agree to participate in our study. * the family is living locally with legal residency status. exclusion criteria: * parent or legal guardian does not agree to participate in our study. * the potential subject has received ipv or opv before 4 months of age in the two-dose schedule group. * the potential subject has one or more contraindications to ipv (although we will note the contraindications).

Keywords: inactivated poliovirus vaccine sabin strain